Util_lib Utils.clone improved

process/Util_lib/process.js

@@ -61,29 +61,46 @@ Utils.isNullOrEmpty = function (pObject)
  * 
  * var original = new MyObject();
  * original.name = "Jotaro";
+ * original.obj1 = {};
+ * original.obj2 = original.obj1;
  * 
  * var copy = ObjectUtils.clone(original);
  * copy.name = "Josuke";
  * 
  * logging.log(original.name != copy.name);    //true
- * logging.log(copy instanceof MyObject());    //true (prototypes are set correctly)
+ * logging.log(copy instanceof MyObject());    //true, prototypes are set correctly
+ * logging.log(copy.obj1 === copy.obj2);       //true, relative object references are kept
  */
 Utils.clone = function (pObject)
 {
-    if (!Utils.isObject(pObject) || pObject === null)
-        return pObject; //Return the value if inObject is not an object
+    var referenceMap = new Map();
+    return _clone(pObject);
     
-    var clonedObject = Array.isArray(pObject) 
-        ? [] 
-        : Object.create(Object.getPrototypeOf(pObject)); //set the prototype of the given object
-
-    for (let key in pObject) 
+    function _clone (pObject)
     {
-        var value = pObject[key];
-        clonedObject[key] = Utils.clone(value); //Recursively (deep) copy for nested objects, including arrays
+        if (typeof pObject !== "object" || pObject === null)
+            return pObject; //Return the value if inObject is not an object
+        
+        if (referenceMap.has(pObject))
+            return referenceMap.get(pObject);
+        
+        var clonedObject = Array.isArray(pObject) 
+            ? [] 
+            : Object.create(Object.getPrototypeOf(pObject)); //set the prototype of the given object
+        
+        /* keeps track of all encountered objects and maps the original to the copy, this makes it possible to:
+           - have the same relative references in the copy as in the original
+           - copy cyclic references without error */
+        referenceMap.set(pObject, clonedObject);
+        
+        for (let key in pObject) 
+        {
+            var value = pObject[key];
+            clonedObject[key] = _clone(value); //Recursively (deep) copy for nested objects, including arrays
+        }
+        
+        return clonedObject;
     }
-
-    return clonedObject;
 }
 
 /**